IU Cancri: a solar-type contact binary with mass transfer

Abstract

We present new CCD photometry of the solar-type contact binary IU Cnc, which was observed from November 2017 to March 2018 with three small telescopes in China. BV light curves imply that IU Cnc is a W-type contact binary with total eclipses. The photometric solution indicates that the mass ratio and fill-out factor are q = 4.104 ± 0.004 and f = 30.2% ± 0.3%, respectively. From all available light minimum times, the orbital period may increase at a rate of dP/dt = +6.93(4) × 10^-7 d yr^-1, which may result from mass transfer from the secondary component to the primary one. With mass transferring, IU Cnc may evolve from a contact configuration into a semi-detached configuration.